Another new E-Class

[PeachtreeSirens]

It's quite likely it was either a fake or a case of bad camera angle.

Anyway, back to the topic at hand...I never realized how big those are. The EC-4 I visited at the College of William & Mary looked rather small relative to its surroundings.

[Xaptus]

Thanks.

I've seen those asc P-50s. So big, you can fit a person in the horn.

Who makes the EC-4s?

[mrboojay]

Dummy cell, eh? Pretty cool.

Do the whelen 2900s have dummy cells, too?

Yes. The 2700s, 2800s, and 2900s all have dummy cells.

Sorry but, the Whelen's do not have dummy cells, only MODs do. And in case there is any confusion between the 2 they look completely different.

https://airraidsirens.com/wiki/index.ph ... ren_Series
https://airraidsirens.com/wiki/index.ph ... 900_series

[Xaptus]

Ohh. Whelen does show single-cell 2900s. Thanks.

[Chicagosiren-hunters]

Yes they so. At the top/bottom of the stack, there are half cells to radiate the sound out instead of up/down

[Xaptus]

Cool! Thanks.
You're filled with lots of knowledge on sirens. I like that!

[freebrickproductions]

That's what I was referring to, didn't realize it was only half of a cell though.

[uncommonsense]

Let's clarify this once and for all:

Each of those speakers on the E-Class (they're made by Kingstar Sound Industry out of Taiwain and the same as used by ATI) is a directional 400W custom. They're oriented 90º apart from each other. One speaker pointing one direction will blast 400W in that direction, 800W if there's one on top of it (2x 400w). I'm not sure what the dispersion radius is on those speakers, but having directional sets of speakers are how all manufacturers started selling omnidirectional electronic sirens as it was the only feasible solution in the early 80s when electronic sirens really took off (ex. Whelen 2000s, Federal 115/1212, ASC Alertronic series). These arrays still serve their purpose, as the Federal DSA makes for a wonderful installation when you don't need full 360º coverage. But otherwise, the use of multiple arrays caused for large and sometimes unsightly installations with the potential for coverage gaps in those areas in between the horns' orientation.

Then enters Whelen, who solved this problem with Bruce Howze's design for the 2700 series in the late 80s. The 2700 takes one 400 watt driver and has the sound radiate off the cell and outward (the patent diagrams how the sound radiates; its actually delightfully complex; but the cells are self-contained). Meanwhile, the problem with Whelen's design is you have to dismantle the whole assembly to replace one driver since the drivers are oriented downward between cells (only rectified in 2007 with the introduction of the 2900 and the EZ-Pull driver).

Thus enter Federal Signal, who, if the patent is to be believed, developed the Mod to address this very shortcoming of Whelen's design. Active cells on the Mod contain 4-400 Watt drivers oriented 90º apart from each other. The sound that is produced dumps into the center of the cell then radiates down onto the cell below it. The "cell sandwich" creates the horn and radiates the sound in a true 360º. This is why you need the dummy cell...you need to complete the horn from the audio produced in the first active cell. There is no such thing as a Mod without a dummy cell. The smallest Mod is the 1004, which will be seen by the eye as having two cells (one active cell with 4-100W drivers and one dummy cell). Each driver is easily replaceable from an access door on the cell. The Mod has evolved into the Mod II, which is a clever reimagining of the Mod. The drivers are attached to curved channels so the siren could be shrunk by maximizing the space inside the unit.

James Biersach comes along and mixes the concepts of the directional speakers and the true 360 omni for the Quadren, where 3-100 watt drivers are self contained in one quarter of the diameter of the cell. Each cell contains an output above and below the drivers, thus completing the horn. Thus you could order the Quadren in a directional or a true omnidirectional formation (my explanation is not in layman's terms...look at the patent for photos that better illustrate the design: http://goo.gl/xG2QbB). The Quadren evolved into the iForce, but honestly, the interior of the iForce looks more like a Mod than it does the Quadren. In fact, the real major difference is that the sound dumps down and then outward from a center channel instead of just downward onto a cell. Neither seems to have been an overwhelming success. There's a few iForces in the wild, but only one Quadren (that we know of) in Mt. Prospect, IL. Please note the iForce still needs a dummy cell while the Quadren was a design all of its own.

So now why are ASC and ATI going back in time and selling these directional arrays? Simple. They're cheap(er). The speakers are outsourced. The Mods and Whelens are designed and built in house. ATI and E-Class speakers are Taiwanese built and off the shelf. The same disadvantages and limitations are there as I described at the start of the post. I suspect ATI uses Kingstar drivers from schematics I've seen. ASC may just be using the shells and inserting Atlas drivers (though I've heard this I've seen no proof; I don't see how it would be cost effective over using the iForce design). But, the advantage is the high degree of customizability. You can orient the speakers however you want. Those Kingstar speakers also make great PA speakers and I've heard anecdotally that ATIs (at least) have great voice intelligibility.

So one question that was asked: would the E-Class be more reliable than an ATI? Well, the problem with ATIs seems to be in the controls, not in the speakers (though Indian Point had issues with their heads rusting [I think...someone check me] because a gel had failed in the speaker seal and water had been seeping in). However, are ASC controls more reliable? It seems that way. But ASC didn't really amp up their electronic business until the last 5 years or so (totally anecdotal and observational of course). But the controller and the quality control thereof is what is going to matter. And ASC did not (from anything I know) change their controller from their prior electronics to the E-Class, so you have a design that seems to be time tested.

Referenced documents:

Modulator Patent: http://goo.gl/JT285Z
Quadren Patent: http://goo.gl/xG2QbB
Whelen 2700 Patent: http://goo.gl/yQl9kv

[coastalsyrolover]

If I may add a comment: I would also like to reference SFO's ATI's and their mocking of the STL-10. Is that human error or are electronic sirens not supposed to do that at all? Also a lot of the modulators I hear here seem to skip a bit on their signals. Controller or speaker problem?

[uncommonsense]

If I may add a comment: I would also like to reference SFO's ATI's and their mocking of the STL-10. Is that human error or are electronic sirens not supposed to do that at all? Also a lot of the modulators I hear here seem to skip a bit on their signals. Controller or speaker problem?

What are you talking about?! SF's ATIs play a recording of the STL-10s for their weekly test. They're absolutely supposed to do that. That's by SF's request. No human error.

As for the Mods skipping on their signals, I'd have to hear it but for the most part, no, Mods are not supposed to skip. But there could be many reasons they might clip. Ex. Whelens on the 440 hz ESC-2020 controller are notorious for clipping.

That all said, my long diatribe was designed to clear up all the confusion that was within the topic. This is way off topic now.

Back to E-Classes.